Liquid crystal display capable of compensating common voltage signal thereof

1. A liquid crystal display, comprising: a plurality of pixel units; a scanning circuit configured to activate the pixel units; a data circuit configured to provide data voltage signals to the activated pixel units via parallel data lines; a feedback line parallel to the data lines; a plurality of signal processing units respectively connected to the data lines; and a common voltage circuit configured to generate a common voltage signal according to a feedback signal received via the feedback line; wherein each pixel unit comprises a coupling member, the coupling member is configured to generate a respective coupling signal according to one of the data voltage signals that is applied to the corresponding activated pixel unit, and superpose the coupling signal to the data voltage signal to form a superposing signal comprising a first cusp wave part formed by the coupling signal and a square wave part formed by the data voltage signal, each of the signal processing units is configured to convert the square wave part of the superposing signal into a second cusp wave part that is independent from the first cusp wave part, the feedback line is configured to provide the feedback signal comprising an averaged first cusp wave part and an averaged second cusp part, to the common voltage circuit, and the common voltage circuit is configured to adjust a reference voltage signal according to the feedback signal, and provide the adjusted reference voltage signal as the common voltage signal to the pixel units.

2. The liquid crystal display of claim 1 , wherein each pixel unit further comprises a pixel electrode, and the coupling member is a coupling capacitor connected between the pixel electrode and a corresponding one of data lines.

3. The liquid crystal display of claim 2 , wherein each pixel unit further comprises a liquid crystal capacitor and a storage capacitor electrically coupled in parallel, a capacitance of the coupling capacitor is substantially the same as a sum of capacitances of the liquid crystal capacitor and the storage capacitor.

4. The liquid crystal display of claim 1 , wherein each of the signal processing units comprises a differentiator for performing a differential calculation on the superposing signal, such that the square wave part of the superposing signal is converted into the second cusp wave part independent from the first cusp wave part of the superposing signal while the first cusp wave part of the superposing signal is bypassed.

5. The liquid crystal display of claim 4 , further comprising a ground line parallel to the feedback line, wherein the signal processing units are disposed at dummy regions between the feedback line and the ground line.

6. The liquid crystal display of claim 5 , wherein the differentiator comprises a differential capacitor and a differential resistor, the differential capacitor is connected between the data line and the feedback line, and the differential resistor is connected between the feedback line and the ground line.

7. The liquid crystal display of claim 6 , wherein the differential capacitor is a parasitic capacitor formed by a superposition of the data line and the feedback line, and the differential resistor is a parasitic resistor of a wire configured for connecting the feedback line to the ground line.

8. The liquid crystal display of claim 1 , wherein the common voltage circuit comprises a filter circuit and a compensating circuit, the filter circuit is configured to remove the averaged second cusp wave part from the feedback signal and extract the averaged first cusp wave part of the feedback signal to the compensating circuit, the compensating circuit is configured to compensate the common voltage signal according to the averaged first cusp wave part of the feedback signal.

9. A liquid crystal display, comprising: a liquid crystal panel comprising a plurality of pixel units arranged in columns; a scanning circuit configured to activate the pixel units; a data circuit configured to provide data voltage signals to the activated pixel units via parallel data lines; a plurality of signal processing units respectively connected to the data lines; and a feedback line parallel to the data lines; wherein each pixel unit comprises a pixel electrode and a coupling element for coupling the pixel electrode to a corresponding data line; when the data voltage signals are applied to the activated pixel units, coupling signals resulted from the data voltage signals are generated by the coupling elements and imposed on the data lines, and the coupling signals respectively superpose the data voltage signals transmitted in the data lines to form superposing signals, each of the superposing signals comprising a first cusp wave part formed by the coupling signal and a square wave part formed by the data voltage signal, the signal processing units are configured to convert the square wave parts of the superposing signals into second cusp wave parts independent from the first cusp wave parts; wherein the feedback line is configured to provide a feedback signal comprising an averaged first cusp wave part and an averaged second cusp wave part to a common voltage circuit, and the common voltage circuit provides a common voltage signal to the pixel units in accordance with the feedback signal.

10. The liquid crystal display of claim 9 , wherein each pixel unit further comprises a pixel electrode, and the coupling signal is induced by the coupling element, the coupling element being a coupling capacitor connected between the pixel electrode and a corresponding one of data lines.

11. The liquid crystal display of claim 10 , wherein each pixel unit further comprises a liquid crystal capacitor and a storage capacitor electrically coupled in parallel, a capacitance of the coupling capacitor is substantially the same as a sum of capacitances of the liquid crystal capacitor and the storage capacitor.

12. The liquid crystal display of claim 9 , wherein each of the signal processing units comprises a differentiator for performing a differential calculation on the superposing signal, such that the square wave part of the superposing signal is converted to the second cusp wave part independent from the first cusp wave part of the superposing signal while the first cusp wave part of the superposing signal is bypassed.

13. The liquid crystal display of claim 12 , further comprising a ground line parallel to the feedback line, wherein the signal processing units are disposed at dummy regions between the feedback line and the ground line.

14. The liquid crystal display of claim 13 , further comprising a ground line, wherein the differentiator comprises a differential capacitor and a differential resistor, the differential capacitor is connected between the data line and the feedback line, and the differential resistor is connected between the feedback line and the ground line.

15. The liquid crystal display of claim 14 , wherein the differential capacitor is a parasitic capacitor formed by a superposition of the data line and the feedback line.

16. The liquid crystal display of claim 15 , wherein the differential resistor is a parasitic resistor of a wire configured for connecting the feedback line to the ground line.

17. The liquid crystal display of claim 9 , wherein the common voltage circuit comprises a filter circuit and a compensating circuit, the filter circuit is configured to remove the averaged second cusp wave part from the feedback signal and extract the averaged first cusp wave part of the feedback signal to the compensating circuit, the compensating circuit is configured to compensate the common voltage signal according to the averaged first cusp wave part of the feedback signal.

18. A liquid crystal display, comprising: a plurality of pixel units; a scanning circuit configured to activate the pixel units; a data circuit configured to provide data voltage signals to the activated pixel units via parallel data lines; a plurality of signal processing units respectively connected to the data lines; and a common voltage circuit configured to generate a common voltage signal; and a feedback line electrically connected between the signal processing units and the common voltage circuit; wherein each pixel unit comprises a coupling member for imposing a coupling signal that is generated in responsive to a corresponding one of the date voltage signals on the data line transmitting the data voltage signal, to form a superposing signal comprising a first cusp wave part formed by the coupling signal and a second square wave part formed by the data voltage signal, each of the signal processing units is configured to output a feedback signal comprising the first wave part and the second wave part to the common voltage circuit based on the superposing signal; each of the signal processing units is configured to convert the square wave part of the superposing signal into a second cusp wave part that is independent from the first cusp wave part; the feedback line is configured to output a feedback signal comprises an averaged first cusp wave part and an averaged second cusp part to the common voltage circuit; the common voltage circuit comprises a compensating circuit for compensating the common voltage signal based on the first wave part of the feedback signal.

19. The liquid crystal display of claim 18 , wherein the common voltage circuit further comprises a filter circuit configured to remove the second cusp wave part from the feedback signal and extract the averaged first cusp wave part of the feedback signal to the compensating circuit.